80mm insulation is not enough.
Hollow block is not a problem. It’s quicker to lay and as long as
Your engineer is happy then that’s all good. It still complied with the same EN standards for solid blocks etc
I would ensure the following from the outside In :
external render as mentioned.
hollow block. (If no other choice).
coat the inside face with a sand/cement layer for air tightness.
then the insulation but I’d want 100mm minimum.